A module or communication system of said type is used in particular in automation technology, wherein, depending on the field of application of the automation system or, as the case may be, of a remote I/O system, the focus is on different aspects of communication. Said aspects are, for example, high speed for specialized functions in control and feedback control engineering, deterministic access/clock synchronism for drive engineering and controls, availability in highly available or fault-tolerant systems, hot-plug-in (extraction and insertion) in particular in systems in the process industry, handling/costs for example in production engineering, communication throughput in particular in the routing of PROFIBUS/Ethernet to communication modules, use in decentralized peripherals for remote I/O and expandability. Today's systems are optimized relatively rigidly in respect of one or more of said aspects, the systems supporting the typical requirements of automation technology such as, for example, cyclical I/O transfer, short response times between central module and the at least one module expanding the central module or between the module and the central module for, for example, alarm messages, clock and time-of-day synchronization and high availability. The data transmission takes place in accordance with deterministic factors taking into account defined response times and is usually initiated by the central module.
Prior art solutions are, for example, serial bus systems for use as local (board-to-board) communication systems based on a daisychain layout or parallel bus systems based on a backplane layout. With serial bus systems, a simple expansion is possible by plugging in modules and said systems have a high degree of flexibility in terms of assembly system (“self-installing variants”). Furthermore said systems are characterized by a small space requirement (in terms of the size of the plugs, mechanical components) and a low power requirement (in terms of the number of drivers, . . . ) and are therefore available as low-cost variants, although they deliver a relatively low performance (serial transmission at bit rates <10 MBd) and relatively high response times. In contrast, parallel systems such as, for example, VME bus or PCI have a relatively high performance (parallel transmission 16-/32-bit), albeit paying a relatively high price for this (four-pin plugs, complex backplanes), a high space requirement (size of the plugs, mechanical components, ASICs, EMC measures), a limited transmission rate (crosstalk, driver technologies, bus structure), a low level of data security (data protection mechanisms), a high power requirement (number of drivers, . . . ) and a low level of flexibility in terms of assembly system (due to fixed backplane layouts).